1. Disconnect battery ground cable.
2. Disconnect numbered and lettered connectors from ECM, Fig. 249.
3. Remove ECM mounting hardware, then the ECM from the passenger compartment.
4. Reverse procedure to install. Replacement Electronic Control Modules are not equipped with engine calibration units (PROM). If PROM is to be reused, care should be taken when removing it from defective ECM. See ``Prom, Replace'' for proper removal procedure.